<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
    <script type="text/javascript">
    let arr = [12,3,45,5,99,1];
/*
    arr.sort(function(n1,n2){
      return n1-n2;
    });
*/
    arr.sort((n1,n2)=>{
      return n1-n2;
    });
    alert(arr);
    </script>
  </head>
  <body>

  </body>
</html>
